(2)  
Installation of the door balance mechanism

 (3)  
Adjustment of the door balance mechanism.

 B.  
The balance mechanisms on the forward and aft cargo doors are equivalent, but the cable lengths are different.

 C.  
You do not have to rig the door again after you install the balance mechanism.

 D.  
The counterbalance mechanism will retract if the counterbalance cable breaks. Refer to AMM 52-31-12/801 to remove the mechanism.

 E.  
Remove the counterbalance assembly to replace the balance mechanism cable.

 TASK 52-31-12-004-002-B00
 2.  Door Balance Mechanism Removal (Fig. 401)______________________________
 A.  Standard Tools and Equipment
 (1)  
Door Support Brace - 2 x 4 inch wood painted red of applicable length to put the door in the open position

 (2)  
Nut - BACN10YRCD (3/8, Self-Locking)

 (3)  
Washer - AN960C616

 B.  
Access

 (1)  
Location Zones
 209 Forward Cargo Door
 219 Aft Cargo Door

 C.  
Remove the Balance Mechanism

 S 844-036-B00
 (1)  
Prepare to remove the balance mechanism:

 (a)  
Remove the lining retainer studs.

 (b)  
Remove the insulation from the door inner skin.

 (c)  
If the counterbalance cable is not broken, do these steps: 1) Open the door until the guide pin comes through the

 adjustment fitting.
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 52-31-12
 ALL  ú ú B02 Page 401 ú Jul 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 2)  Remove the screw and sleeve from the guide pin if they are installed.
 3)  Put the nut and the washer on the counterbalance shaft against the adjustment fitting to hold the spring and stop counterbalance operation (Fig. 401, detail A).
 (d)  
If the counterbalance cable is broken, do the door balance mechanism repair (AMM 52-31-12/801).

 (e)  
Use the door support brace to put the cargo door in a position to remove the balance mechanism.

 (f)  
Make sure the balance mechanism cable is loose.

 S 024-039-B00
 (2)  Remove the counterbalance assembly.
 WARNING: MAKE SURE THERE IS NO TENSION ON THE BALANCE MECHANISM
_______ CABLE BEFORE YOU REMOVE THE COUNTERBALANCE ASSEMBLY. IF THE COUNTERBALANCE SPRING IS NOT HELD BY THE NUT, THE CABLE CAN CAUSE INJURY WHEN IT ACCIDENTALLY RETRACTS.
 (a)  
Remove the five attach bolts from the counterbalance assembly.

 (b)  
Remove the assembly from the door.

 S 034-058-B00
 (3)  
Disconnect the balance cable from the counterblance.

 (a)  
Remove the cable retaining screw and the plate from the drum.

 (b)  
Disconnect the balance mechanism cable from the drum.

 (c)  
Let the cable stay on the airplane.

 TASK 52-31-12-404-018-B00
 3.  Balance Mechanism Installation (Fig. 401)
______________________________
 A.  Standard Tools and Equipment
 (1)  
Door Support Brace - 2 x 4 inch wood painted red of applicable length to put the door in the open position

 (2)  
Nut - BACN10YRCD (3/8, Self-Locking)

 (3)  
Washer - AN960C616

 B.  
Access

 (1)  
Location Zones
 209 Forward Cargo Door
 219 Aft Cargo Door

 C.  
Procedure

 S 844-041-B00
 (1)  
Prepare to install the door balance mechanism.

 (a)  
Make sure there is a nut and washer on the counterbalance shaft against the adjustment fitting (Fig. 401). Refer to 52-31-12/801 to install the nut if necessary.

 NOTE: This will hold the spring and stop counterbalance
____
 operation.

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